Recurrent inhibition of the monosynaptic reflex in the upper caudal cord of the cat

Summary In spinal cats both ipsi- and contralateral antidromic volleys in the 3rd sacral ventral roots produce recurrent inhibition of the monosynaptic reflex evoked by stimulation of the 1st caudal dorsal root and recorded from the corresponding ventral root.     

Recurrent inhibition of the monosynaptic reflex in the upper caudal cord of the cat.

In spinal cats both ipsi- and contralateral antidromic volleys in the 3rd sacral ventral roots produce recurrent inhibition of the monosynaptic reflex evoked by stimulation of the 1st caudal dorsal root and recorded from the corresponding ventral root.     

The effect of L-Dopa on the spinal monosynaptic mass reflex

Summary After i. v. injection of reserpine, the monosynaptic mass reflex (MSMR) is depressed in spinalized cats. However, the complete recovery of MSMR was obtained 30 min after L-Dopa application. Pimozide, a dopamine-receptor blocking agent, blocked this action of L-Dopa. It is presumed that dopaminergic receptors are involved in the action of L-Dopa on spinal MSMR.     

Skeletomotor and fusimotor control of gastrocnemius muscle from Deiters' nucleus

Riassunto La stimolazione ripetitiva del nucleo di Deiters produce la contrazione del muscolo gastrocnemio, che si accompagna ad una scarica afferente fusale. La risposta dei recettori fusali dipende non soltanto dall'attività delle fibre, ma anche da quella di fibre fusimotorie di più grande diametro, probabilmente di natura .

---

---

This investigation was supported by PHS research grant No. NB-02990-05 from the National Institute of Neurological Diseases and Blindness, N.I.H., Public health Service (USA).     

Descending pathways with monosynaptic action on motoneurones

Zusammenfassung Motoneuronen, sowohl zu Streckwie Beugemuskeln, werden von absteigenden Bahnen des Rückenmarkes supraspinalen Ursprungs monosynaptisch beeinflusst. Es konnte gezeigt werden, dass die Wirkung an den Motoneuronen der Streckmuskeln aus dem Nucleus vestibularis lateralis (Deiters) stammt.     

Antidromic inhibition of presumed fusimotor neurones by repetitive stimulation of the ventral root in the decerebrate cat

Résumé On a enregistré des décharges de 17 fibres fusimotrices dont on suppose l'existence dans les filaments de racines ventrales des chats décérébrés. 8 fibres ont été inhibées par stimulation répétée de la portion centrale isolée du reste de la racine ventrale. Ces résultats montrent qu'il existe une inhibition antidromique dans les neurones fusimoteurs.     

The mode of cerebral activation of red nucleus neurones

Zusammenfassung Elektrische Reizung des sensorimotorischen Kortex ruft monosynaptische EPSPs, in den grossen Zellen des N. ruber der Katze hervor (RNZellen). Die kortikalen Punkte, von denen EPSPs hervorgerufen werden können, sind somatotopisch so angeordnet, dass sie mit der histologischen Projektion der kortikorubralen Fasern übereinstimmen. Membran-Hyper-Polarisierung, die stark genug ist, um EPSPs vom N. interpositus zu vergrössern, hat keinen Einfluss auf Amplituden oder Zeitfluss von cerebral hervorgebrachten EPSPs. Es wird daraus geschlossen, dass kortiko-rubrale Fasern synaptischen Kontakt mit den Dendriten von RN-Zellen machen.     

Intracellular recordings from Deiters' neurons in response to saccular and oculomotor nucleus stimulations

Summary 2 populations of cells were found in the Deiters' nucleus responsive to direct electrical stimulation of the ipsilateral saccule. Only those Deiters' neurons activated monosynaptically from the saccule could be driven antidromically from the oculomotor nucleus. Such an intracellular study provides strong evidence for a tri-neuronal arc in the sacculo-ocular reflex for vertical eye movements.Acknowledgment. This study was supported by the Medical Faculty Research Grant No. 377/004/03, University of Hong Kong.     

The action of conformationally restricted analogues of GABA onLimulus andHelix central neurones

Summary Intracellular recordings have been made from GABA sensitive neurones in the central nervous system ofLimulus andHelix. The following conformationally restricted analogues of GABA all possessed GABA-like activity onLimulus neurones andHelix excitatory GABA receptors: muscimol, thiomuscimol, THIP, isoguvacine and piperidine-4-carboxylic acid. It is suggested that GABA interacts with these receptors in a partially extended and almost planar conformation.     

Sensitivity of cortical neurones to acetylcholine

Resumé Sur 1367 neurones de l'écorce cérébrale du chat, examinés directement par la méthode iontophorétique, il a été possible d'en stimuler 200 par l'acétylcholine. Tous les neurones sont fortement excités par leL-glutamate et inhibés par l'acide -aminobutyrique.     

The action of muscimol on neurones of the substantia nigra of the rat

Summary Muscimol and GABA applied microintophoretically onto nigral neurones reduce the discharge rate of most of these cells. Bicuculline reversibly antagonizes the action of muscimol. I.p. applied muscimol reduces the firing rate of about half of the nigral cells tested.The valuable assistance of Mrs Alice Fonjallaz is warmly acknowledged.